The board of the International Monetary Fund has approved a two-year, $17 billion loan to Ukraine, the IMF announced Wednesday.

The loan serves as a rescue package to prevent a collapse of Ukraine's economy, which has been thrown into turmoil amid recent unrest. Russia annexed the region of Crimea last month, and it has continued its troop presence in eastern Ukraine, putting the government of Russian President Vladimir Putin in a standoff with much of the west.

The IMF promised the aid in March, hinging it on reforms that included raising taxes, freezing the minimum wage, and raising energy prices.

In a statement, U.S. Treasury Secretary Jack Lew said the aid package represented a "crucial milestone" for Ukraine, and he promised the U.S. would impose further "costs" on Russia if it did not work to de-escalate the situation.

"Today’s final approval for the $17 billion IMF program marks a crucial milestone for Ukraine. The IMF program, in conjunction with bilateral assistance from the United States and other nations, will enable Ukraine to build on the progress already achieved to overcome deep-seated economic challenges and help the country return to a path of economic stability and growth," Lew said.

Lew added he is confident Ukraine would enact the required reforms.

"From my recent conversations with Ukrainian officials, including Prime Minister Yatsenyuk, Finance Minister Shlapak, and central bank Governor Kubiv, it is clear that Ukraine is committed to implementing the reforms included in the IMF program, and these reforms are critical to limiting continued vulnerability to regional pressures," he said.